The
knees provide stable support for the body and allow the legs to
bend and straighten. Both flexibility and stability are needed
for standing and for motions like walking, running, crouching,
jumping, and turning.
Several
kinds of supporting and moving parts, including bones, cartilage,
muscles, ligaments, and tendons, help the knees do their job.
Any of these parts can be involved in pain or dysfunction.
What Causes
Knee Problems?
There
are two general kinds of knee problems: mechanical and inflammatory.
Mechanical
Knee Problems
Some
knee problems result from injury, such as a direct blow or sudden
movements that strain the knee beyond its normal range of movement.
Other problems, such as osteoarthritis in the knee, result from
wear and tear on its parts.
Inflammatory
Knee Problems
Inflammation
that occurs in certain rheumatic diseases, such as rheumatoid
arthritis and systemic lupus erythematosus, can damage the knee.
Joint Basics
The
point at which two or more bones are connected is called a joint.
In all joints, the bones are kept from grinding against each other
by padding called cartilage. Bones are joined to bones by strong,
elastic bands of tissue called ligaments. Tendons are tough cords
of tissue that connect muscle to bone. Muscles work in opposing
pairs to bend and straighten joints. While muscles are not technically
part of a joint, they're important because strong muscles help
support and protect joints.
What Are the
Parts of the Knee?
Like
any joint, the knee is composed of bones and cartilage, ligaments,
tendons, and muscles (see the diagram).
Bones
and Cartilage
The
knee joint is the junction of three bones: the femur (thigh
bone or upper leg bone), the tibia (shin bone or larger bone of
the lower leg), and the patella (knee cap). The patella is 2 to
3 inches wide and 3 to 4 inches long. It sits over the other bones
at the front of the knee joint and slides when the leg moves.
It protects the knee and gives leverage to muscles.
The
ends of the three bones in the knee joint are covered with articular
cartilage, a tough, elastic material that helps absorb shock
and allows the knee joint to move smoothly. Separating the bones
of the knee are pads of connective tissue. One pad is called
a meniscus (muh-NISS-kus). The plural is menisci (muh-NISS-sky).
The menisci are divided into two crescent-shaped discs positioned
between the tibia and femur on the outer and inner sides of each
knee. The two menisci in each knee act as shock absorbers,
cushioning the lower part of the leg from the weight of the rest
of the body as well as enhancing stability.
Muscles
There
are two groups of muscles at the knee. The quadriceps muscle comprises
four muscles on the front of the thigh that work to straighten
the leg from a bent position. The hamstring muscles, which bend
the leg at the knee, run along the back of the thigh from the
hip to just below the knee. Keeping these muscles strong with
exercises such as walking up stairs or riding a stationary bicycle
helps support and protect the knee.
Tendons
and Ligaments
The
quadriceps tendon connects the quadriceps muscle to the patella
and provides the power to extend the leg. Four ligaments connect
the femur and tibia and give the joint strength and stability:
The
medial collateral ligament (MCL) provides stability to the
inner (medial) part of the knee.
The lateral collateral ligament (LCL) provides stability
to the outer (lateral) part of the knee.
The anterior cruciate ligament (ACL), in the center of
the knee, limits rotation and the forward movement of the tibia.
The posterior cruciate ligament (PCL), also in the center
of the knee, limits backward movement of the tibia.
Other ligaments are part of the knee capsule, which is a protective,
fiber-like structure that wraps around the knee joint. Inside
the capsule, the joint is lined with a thin, soft tissue called
synovium.
How Are
Knee Problems Diagnosed?
Doctors
use several methods to diagnose knee problems.
Medical
history--The patient tells the doctor details about symptoms
and about any injury, condition, or general health problem that
might be causing the pain.
Physical
examination--The doctor bends, straightens, rotates (turns),
or presses on the knee to feel for injury and discover the limits
of movement and the location of pain. The patient may be asked
to stand, walk, or squat to help the doctor assess the knee's
function.
Diagnostic
tests--The doctor uses one or more tests to determine the
nature of a knee problem.
X
ray (radiography)--An x-ray beam is passed through the knee
to produce a two-dimensional picture of the bones.
Computerized axial tomography (CAT) scan--X rays lasting
a fraction of a second are passed through the knee at different
angles, detected by a scanner, and analyzed by a computer. This
produces a series of clear cross-sectional images ("slices")
of the knee tissues on a computer screen. CAT scan images show
soft tissues such as ligaments or muscles more clearly than conventional
x rays. The computer can combine individual images to give a three-dimensional
view of the knee.
Bone scan (radionuclide scanning)--A very small amount
of radioactive material is injected into the patient's bloodstream
and detected by a scanner. This test detects blood flow to the
bone and cell activity within the bone and can show abnormalities
in these processes that may aid diagnosis.
Magnetic resonance imaging (MRI)--Energy from a powerful
magnet (rather than x rays) stimulates knee tissue to produce
signals that are detected by a scanner and analyzed by a computer.
This creates a series of cross-sectional images of a specific
part of the knee. An MRI is particularly useful for detecting
soft tissue damage or disease. Like a CAT scan, a computer is
used to produce three-dimensional views of the knee during MRI.
Arthroscopy--The doctor manipulates a small, lighted optic
tube (arthroscope) that has been inserted into the joint through
a small incision in the knee. Images of the inside of the knee
joint are projected onto a television screen. While the arthroscope
is inside the knee joint, removal of loose pieces of bone or cartilage
or the repair of torn ligaments and menisci is also possible.
Biopsy--The doctor removes tissue to examine under a microscope.
Knee Injuries and Problems
Knee Injuries
and Problems
Arthritis
What
Is Arthritis of the Knee?
Arthritis
of the knee is most often osteoarthritis. In this disease, the
cartilage in the joint gradually wears away. In rheumatoid arthritis,
which can also affect the knees, the joint becomes inflamed and
cartilage may be destroyed.* Arthritis not only affects joints;
it can also affect supporting structures such as muscles, tendons,
and ligaments.
Osteoarthritis
may be caused by excess stress on the joint from deformity, repeated
injury, or excess weight. It most often affects middle-aged and
older people. A young person who develops osteoarthritis may have
an inherited form of the disease or may have experienced continuous
irritation from an unrepaired torn meniscus or other injury. Rheumatoid
arthritis often affects people at an earlier age than osteoarthritis.
*
The National Institute of Arthritis and Musculoskeletal and Skin
Diseases Information Clearinghouse has separate publications on
osteoarthritis, rheumatoid arthritis, and knee replacement. See
the end of this booklet for contact information.
Signs
and Diagnosis
Someone
who has arthritis of the knee may experience pain, swelling, and
a decrease in knee motion. A common symptom is morning stiffness
that lessens as the person moves around. Sometimes the joint locks
or clicks when the knee is bent and straightened, but these signs
may occur in other knee disorders as well. The doctor may confirm
the diagnosis by performing a physical examination and examining
x rays, which typically show a loss of joint space. Blood tests
may be helpful for diagnosing rheumatoid arthritis, but other
tests may be needed too. Analyzing fluid from the knee joint may
be helpful in diagnosing some kinds of arthritis. The doctor may
use arthroscopy to directly see damage to cartilage, tendons,
and ligaments and to confirm a diagnosis, but arthroscopy is usually
done only if a repair procedure is to be performed.
Treatment
Most
often osteoarthritis of the knee is treated with pain-reducing
medicines, such as aspirin or acetaminophen (Tylenol*); nonsteroidal
anti-inflammatory drugs (NSAIDs), such as ibuprofen (Motrin, Nuprin,
Advil); and exercises to restore joint movement and strengthen
the knee. Losing excess weight can also help people with osteoarthritis.
Rheumatoid
arthritis of the knee may require physical therapy and more powerful
medications. In people with arthritis of the knee, a seriously
damaged joint may need to be replaced with an artificial one.
(A new procedure designed to stimulate the growth of cartilage
by using a patient's own cartilage cells is being used experimentally
to repair cartilage injuries at the end of the femur at the knee.
It is not, however, a treatment for arthritis.)
*
Brand names included in this booklet are provided as examples
only, and their inclusion does not mean that these products are
endorsed by the National Institutes of Health or any other Government
agency. Also, if a particular brand name is not mentioned, this
does not mean or imply that the product is unsatisfactory.
Cartilage
Injuries and Disorders
What
Is Chondromalacia?
Chondromalacia
(KON-dro-mah-LAY-she-ah), also called chondromalaciapatellae,
refers to softening of the articular cartilage of the knee cap.
This disorder occurs most often in young adults and can be caused
by injury, overuse, parts out of alignment, or muscle weakness.
Instead of gliding smoothly across the lower end of the thigh
bone, the knee cap rubs against it, thereby roughening the cartilage
underneath the knee cap. The damage may range from a slightly
abnormal surface of the cartilage to a surface that has been worn
away to the bone. Chondromalacia related to injury occurs when
a blow to the knee cap tears off either a small piece of cartilage
or a large fragment containing a piece of bone (osteochondral
fracture).
Symptoms
and Diagnosis
The
most frequent symptom is a dull pain around or under the knee
cap that worsens when walking down stairs or hills. A person may
also feel pain when climbing stairs or when the knee bears weight
as it straightens. The disorder is common in runners and is also
seen in skiers, cyclists, and soccer players. A patient's description
of symptoms and a followup x ray usually help the doctor make
a diagnosis. Although arthroscopy can confirm the diagnosis, it's
not performed unless the condition requires extensive treatment.
Treatment
Many
doctors recommend that patients with chondromalacia perform low-impact
exercises that strengthen muscles, particularly the inner part
of the quadriceps, without injuring joints. Swimming, riding a
stationary bicycle, and using a cross-country ski machine are
acceptable as long as the knee doesn't bend more than 90 degrees.
Electrical stimulation may also be used to strengthen the muscles.
If these treatments don't improve the condition, the doctor may
perform arthroscopic surgery to smooth the surface of the cartilage
and "wash out" the cartilage fragments that cause the
joint to catch during bending and straightening. In more severe
cases, surgery may be necessary to correct the angle of the knee
cap and relieve friction with the cartilage or to reposition parts
that are out of alignment.
Injuries
to the Meniscus
What
Causes Injuries to the Meniscus?
The
meniscus is easily injured by the force of rotating the knee while
bearing weight. A partial or total tear may occur when a person
quickly twists or rotates the upper leg while the foot stays still
(for example, when dribbling a basketball around an opponent or
turning to hit a tennis ball). If the tear is tiny, the meniscus
stays connected to the front and back of the knee; if the tear
is large, the meniscus may be left hanging by a thread of cartilage.
The seriousness of a tear depends on its location and extent.
Symptoms
Generally,
when people injure a meniscus, they feel some pain, particularly
when the knee is straightened. If the pain is mild, the person
may continue moving. Severe pain may occur if a fragment of the
meniscus catches between the femur and the tibia. Swelling may
occur soon after injury if blood vessels are disrupted, or swelling
may occur several hours later if the joint fills with fluid produced
by the joint lining (synovium) as a result of inflammation. If
the synovium is injured, it may become inflamed and produce fluid
to protect itself. This makes the knee swell. Sometimes, an injury
that occurred in the past but was not treated becomes painful
months or years later, particularly if the knee is injured a second
time. After any injury, the knee may click, lock, or feel weak.
Although symptoms of meniscal injury may disappear on their own,
they frequently persist or return and require treatment.
Diagnosis
In
addition to listening to the patient's description of the onset
of pain and swelling, the doctor may perform a physical examination
and take x rays of the knee. The examination may include a test
in which the doctor bends the leg, then rotates the leg outward
and inward while extending it. Pain or an audible click suggests
a meniscal tear. An MRI may be recommended to confirm the diagnosis.
Occasionally, the doctor may use arthroscopy to help diagnose
and treat a meniscal tear.
Treatment
If
the tear is minor and the pain and other symptoms go away, the
doctor may recommend a muscle-strengthening program. Exercises
for meniscal problems are best started with guidance from a doctor
and physical therapist or exercise therapist. The therapist will
make sure that the patient does the exercises properly and without
risking new or repeat injury. The following exercises after injury
to the meniscus are designed to build up the quadriceps and hamstring
muscles and increase flexibility and strength.
Warming
up the joint by riding a stationary bicycle, then straightening
and raising the leg (but not straightening it too much).
Extending the leg while sitting (a weight may be worn on the ankle
for this exercise).
Raising the leg while lying on the stomach.
Exercising in a pool (walking as fast as possible in chest-deep
water, performing small flutter kicks while holding onto the side
of the pool, and raising each leg to 90 degrees in chest-deep
water while pressing the back against the side of the pool).
If the tear is more extensive, the doctor may perform arthroscopic
or open surgery to see the extent of injury and to repair the
tear. The doctor can sew the meniscus back in place if the patient
is relatively young, if the injury is in an area with a good blood
supply, and if the ligaments are intact. Most young athletes are
able to return to active sports after meniscus repair.
If
the patient is elderly or the tear is in an area with a poor blood
supply, the doctor may cut off a small portion of the meniscus
to even the surface. In some cases, the doctor removes the entire
meniscus. However, osteoarthritis is more likely to develop in
the knee if the meniscus is removed. Medical researchers are investigating
a procedure called an allograft, in which the surgeon replaces
the meniscus with one from a cadaver. A grafted meniscus is fragile
and will shrink and tear easily. Researchers have also attempted
to replace a meniscus with an artificial one, but this procedure
is even less successful than an allograft.
Recovery
after surgical repair takes several weeks, and postoperative activity
is slightly more restricted than when the meniscus is removed.
Nevertheless, putting weight on the joint actually fosters recovery.
Regardless of the form of surgery, rehabilitation usually includes
walking, bending the legs, and doing exercises that stretch and
build up leg muscles. The best results of treatment for meniscal
injury are obtained in people who do not show articular cartilage
changes and who have an intact ACL.
Ligament
Injuries
What
Are the Causes of Anterior and Posterior Cruciate Ligament Injuries?
Injury
to the cruciate ligaments is sometimes referred to as a "sprain."*
The ACL is most often stretched or torn (or both) by a sudden
twisting motion (for example, when the feet are planted one way
and the knees are turned another).
The
PCL is most often injured by a direct impact, such as in an automobile
accident or football tackle.
*
The National Institute of Arthritis and Musculoskeletal and Skin
Diseases Information Clearinghouse has a separate publication
on sprains and strains. See the end of this booklet for contact
information.
Symptoms
and Diagnosis
Injury
to a cruciate ligament may not cause pain. Rather, the person
may hear a popping sound, and the leg may buckle when he or she
tries to stand on it. The doctor may perform several tests to
see whether the parts of the knee stay in proper position when
pressure is applied in different directions. A thorough examination
is essential. An MRI is very accurate in detecting a complete
tear, but arthroscopy may be the only reliable means of detecting
a partial one.
Treatment
For
an incomplete tear, the doctor may recommend that the patient
begin an exercise program to strengthen surrounding muscles. The
doctor may also prescribe a brace to protect the knee during activity.
For a completely torn ACL in an active athlete and motivated person,
the doctor is likely to recommend surgery. The surgeon may reattach
the torn ends of the ligament or reconstruct the torn ligament
by using a piece (graft) of healthy ligament from the patient
(autograft) or from a cadaver (allograft). Although synthetic
ligaments have been tried in experiments, the results have not
been as good as with human tissue. One of the most important elements
in a patient's successful recovery after cruciate ligament surgery
is a 4- to 6-month exercise and rehabilitation program that may
involve using special exercise equipment at a rehabilitation or
sports center. Successful surgery and rehabilitation will allow
the patient to return to a normal lifestyle.
What
Is the Most Common Cause of Medial and Lateral Collateral Ligament
Injuries?
The
MCL is more easily injured than the LCL. The cause is most often
a blow to the outer side of the knee that stretches and tears
the ligament on the inner side of the knee. Such blows frequently
occur in contact sports like football or hockey.
Symptoms
and Diagnosis
When
injury to the MCL occurs, a person may feel a pop and the knee
may buckle sideways. Pain and swelling are common. A thorough
examination is needed to determine the kind and extent of the
injury. To diagnose a collateral ligament injury, the doctor exerts
pressure on the side of the knee to determine the degree of pain
and the looseness of the joint. An MRI is helpful in diagnosing
injuries to these ligaments.
Treatment
Most
sprains of the collateral ligaments will heal if the patient follows
a prescribed exercise program. In addition to exercise, the doctor
may recommend ice packs to reduce pain and swelling and a small
sleeve-type brace to protect and stabilize the knee. A sprain
may take 2 to 4 weeks to heal. A severely sprained or torn collateral
ligament may be accompanied by a torn ACL, which usually requires
surgical repair.
Tendon Injuries
and Disorders
What
Causes Tendinitis and Ruptured Tendons?
Knee
tendon injuries range from tendinitis (inflammation of a tendon)
to a ruptured (torn) tendon. If a person overuses a tendon during
certain activities such as dancing, cycling, or running, the tendon
stretches like a worn-out rubber band and becomes inflamed. Also,
trying to break a fall may cause the quadriceps muscles to contract
and tear the quadriceps tendon above the patella or the patellar
tendon below the patella. This type of injury is most likely to
happen in older people whose tendons tend to be weaker. Tendinitis
of the patellar tendon is sometimes called jumper's knee because
in sports that require jumping, such as basketball, the muscle
contraction and force of hitting the ground after a jump strain
the tendon. After repeated stress, the tendon may become inflamed
or tear.
Symptoms
and Diagnosis
People
with tendinitis often have tenderness at the point where the patellar
tendon meets the bone. In addition, they may feel pain during
running, hurried walking, or jumping. A complete rupture of the
quadriceps or patellar tendon is not only painful, but also makes
it difficult for a person to bend, extend, or lift the leg against
gravity. If there is not much swelling, the doctor will be able
to feel a defect in the tendon near the tear during a physical
examination. An x ray will show that the patella is lower than
normal in a quadriceps tendon tear and higher than normal in a
patellar tendon tear. The doctor may use an MRI to confirm a partial
or total tear.
Treatment
Initially,
the doctor may ask a patient with tendinitis to rest, elevate,
and apply ice to the knee and to take medicines such as aspirin
or ibuprofen to relieve pain and decrease inflammation and swelling.
If the quadriceps or patellar tendon is completely ruptured, a
surgeon will reattach the ends. After surgery, the patient will
wear a cast for 3 to 6 weeks and use crutches. For a partial tear,
the doctor might apply a cast without performing surgery.
Rehabilitating
a partial or complete tear of a tendon requires an exercise program
that is similar to but less vigorous than that prescribed for
ligament injuries. The goals of exercise are to restore the ability
to bend and straighten the knee and to strengthen the leg to prevent
repeat injury. A rehabilitation program may last 6 months, although
the patient can return to many activities before then.
What
Causes Osgood-Schlatter Disease?
Osgood-Schlatter
disease is caused by repetitive stress or tension on part of the
growth area of the upper tibia (the apophysis). It is characterized
by inflammation of the patellar tendon and surrounding soft tissues
at the point where the tendon attaches to the tibia. The disease
may also be associated with an injury in which the tendon is stretched
so much that it tears away from the tibia and takes a fragment
of bone with it. The disease most commonly affects active young
people, particularly boys between the ages of 10 and 15, who play
games or sports that include frequent running and jumping.
Symptoms
and Diagnosis
People
with this disease experience pain just below the knee joint that
usually worsens with activity and is relieved by rest. A bony
bump that is particularly painful when pressed may appear on the
upper edge of the tibia (below the knee cap). Usually, the motion
of the knee is not affected. Pain may last a few months and may
recur until the child's growth is completed.
Osgood-Schlatter
disease is most often diagnosed by the symptoms. An x ray may
be normal, or show an injury, or, more typically, show that the
growth area is in fragments.
Treatment
Usually,
the disease resolves without treatment. Applying ice to the knee
when pain begins helps relieve inflammation and is sometimes used
along with stretching and strengthening exercises. The doctor
may advise the patient to limit participation in vigorous sports.
Children who wish to continue moderate or less stressful sports
activities may need to wear knee pads for protection and apply
ice to the knee after activity. If there is a great deal of pain,
sports activities may be limited until discomfort becomes tolerable.
What
Causes Iliotibial Band Syndrome?
This
is an overuse condition in which inflammation results when a band
of a tendon rubs over the outer bone (lateral condyle) of the
knee. Although iliotibial band syndrome may be caused by direct
injury to the knee, it is most often caused by the stress of long-term
overuse, such as sometimes occurs in sports training.
Symptoms
and Diagnosis
A
person with this syndrome feels an ache or burning sensation at
the side of the knee during activity. Pain may be localized at
the side of the knee or radiate up the side of the thigh. A person
may also feel a snap when the knee is bent and then straightened.
Swelling is usually absent and knee motion is normal. The diagnosis
of this disorder is typically based on the symptoms, such as pain
at the outer bone, and exclusion of other conditions with similar
symptoms.
Treatment
Usually,
iliotibial band syndrome disappears if the person reduces activity
and performs stretching exercises followed by muscle-strengthening
exercises. In rare cases when the syndrome doesn't disappear,
surgery may be necessary to split the tendon so it isn't stretched
too tightly over the bone.
Other Knee
Injuries
What
Is Osteochondritis Dissecans?
Osteochondritis
dissecans results from a loss of the blood supply to an area of
bone underneath a joint surface and usually involves the knee.
The affected bone and its covering of cartilage gradually loosen
and cause pain. This problem usually arises spontaneously in an
active adolescent or young adult. It may be due to a slight blockage
of a small artery or to an unrecognized injury or tiny fracture
that damages the overlying cartilage. A person with this condition
may eventually develop osteoarthritis.
Lack
of a blood supply can cause bone to break down (avascular necrosis).*
The involvement of several joints or the appearance of osteochondritis
dissecans in several family members may indicate that the disorder
is inherited.
*
The National Institute of Arthritis and Musculoskeletal and Skin
Diseases Information Clearinghouse has a separate publication
on avascular necrosis. See the end of this booklet for contact
information.
Symptoms
and Diagnosis
If
normal healing doesn't occur, cartilage separates from the diseased
bone and a fragment breaks loose into the knee joint, causing
weakness, sharp pain, and locking of the joint. An x ray, MRI,
or arthroscopy can determine the condition of the cartilage and
can be used to diagnose osteochondritis dissecans.
Treatment
If
cartilage fragments have not broken loose, a surgeon may fix them
in place with pins or screws that are sunk into the cartilage
to stimulate a new blood supply.
If
fragments are loose, the surgeon may scrape down the cavity to
reach fresh bone and add a bone graft and fix the fragments in
position. Fragments that cannot be mended are removed, and the
cavity is drilled or scraped to stimulate new cartilage growth.
Research is being done to assess the use of cartilage cell and
other tissue transplants to treat this disorder.
What
Is Plica Syndrome?
Plica
(PLI-kah) syndrome occurs when plicae (bands of synovial tissue)
are irritated by overuse or injury. Synovial plicae are the remains
of tissue pouches found in the early stages of fetal development.
As
the fetus develops, these pouches normally combine to form one
large synovial cavity. If this process is incomplete, plicae remain
as four folds or bands of synovial tissue within the knee. Injury,
chronic overuse, or inflammatory conditions are associated with
this syndrome.
Symptoms
and Diagnosis
People
with this syndrome are likely to experience pain and swelling,
a clicking sensation, and locking and weakness of the knee. Because
the symptoms are similar to those of some other knee problems,
plica syndrome is often misdiagnosed. Diagnosis usually depends
on excluding other conditions that cause similar symptoms.
Treatment
The
goal of treatment is to reduce inflammation of the synovium and
thickening of the plicae. The doctor usually prescribes medicine
such as ibuprofen to reduce inflammation. The patient is also
advised to reduce activity, apply ice and an elastic bandage to
the knee, and do strengthening exercises. A cortisone injection
into the plica folds helps about half of those treated. If treatment
fails to relieve symptoms within 3 months, the doctor may recommend
arthroscopic or open surgery to remove the plicae.
What Kinds
of Doctors Treat Knee Problems?
Extensive injuries and diseases of the knees are
usually treated by an orthopaedic surgeon, a doctor who has been
trained in the nonsurgical and surgical treatment of bones, joints,
and soft tissues such as ligaments, tendons, and muscles. Patients
seeking nonsurgical treatment of arthritis of the knee may also
consult a rheumatologist (a doctor specializing in the diagnosis
and treatment of arthritis and related disorders).
How Can
People Prevent Knee Problems?
Some
knee problems, such as those resulting from an accident, can't
be foreseen or prevented. However, a person can prevent many knee
problems by following these suggestions:
Before
exercising or participating in sports, warm up by walking or riding
a stationary bicycle, then do stretches. Stretching the muscles
in the front of the thigh (quadriceps) and back of the thigh (hamstrings)
reduces tension on the tendons and relieves pressure on the knee
during activity.
Strengthen the leg muscles by doing specific exercises (for example,
by walking up stairs or hills, or by riding a stationary bicycle).
A supervised workout with weights is another way to strengthen
the leg muscles that support the knee.
Avoid sudden changes in the intensity of exercise. Increase the
force or duration of activity gradually.
Wear
shoes that both fit properly and are in good condition to help
maintain balance and leg alignment when walking or running. Knee
problems can be caused by flat feet or overpronated feet (feet
that roll inward). People can often reduce some of these problems
by wearing special shoe inserts (orthotics). Maintain a healthy
weight to reduce stress on the knee. Obesity increases the risk
of degenerative (wearing) conditions such as osteoarthritis of
the knee.
What Types of Exercise Are Most Suitable for Someone With Knee
Problems?
Three types
of exercise are best for people with arthritis:
Range-of-motion
exercises help maintain normal joint movement and relieve stiffness.
This type of exercise helps maintain or increase flexibility.
Strengthening exercises help keep or increase muscle strength.
Strong muscles help support and protect joints affected by arthritis.
Aerobic or endurance exercises improve function of the heart and
circulation and help control weight. Weight control can be important
to people who have arthritis because extra weight puts pressure
on many joints. Some studies show that aerobic exercise can reduce
inflammation in some joints.
Where Can People Find More Information About Knee Problems?
National
Institute of Arthritis and Musculoskeletal and Skin
Diseases Information Clearinghouse
National Institutes of Health
1 AMS Circle
Bethesda, MD 20892-3675
Phone: 301-495-4484 or
877-22-NIAMS (226-4267) (free of charge)
TTY: 301-565-2966
Fax: 301-718-6366
http://www.niams.nih.gov/
The
clearinghouse provides information about various forms of arthritis
and rheumatic disease and bone, muscle, and skin diseases.
It distributes patient and professional education materials and
refers people to other sources of information. Additional information
and updates can also be found on the NIAMS Web site.
American Academy of Orthopaedic Surgeons
P.O. Box 2058
Des Plaines, IL 60017
Phone: 800-824-BONE (2663) (free of charge)
www.aaos.org
The academy provides education and practice management
services for orthopaedic surgeons and allied health professionals.
It also serves as an advocate for improved patient care and informs
the public about the science of orthopaedics. The orthopaedist's
scope of practice includes disorders of the body's bones, joints,
ligaments, muscles, and tendons. For a single copy of an AAOS
brochure, send a self-addressed stamped envelope to the address
above or visit the AAOS Web site.
American College of Rheumatology
1800 Century Place, Suite 250
Atlanta, GA 30329
Phone: 404-633-3777
Fax: 404-633-1870
www.rheumatology.org
This national professional organization can provide
referrals to rheumatologists and allied health professionals,
such as physical therapists. One-page fact sheets are available
on various forms of arthritis. Lists of specialists by geographic
area and fact sheets are also available on this Web site.
American Physical Therapy Association
1111 N. Fairfax Street
Alexandria, VA 22314
Phone: 800-999-APTA (2782) (free of charge)
www.apta.org
The association publishes a free brochure titled
"Taking Care of the Knees."
Arthritis Foundation
1330 West Peachtree Street
Atlanta, GA 30309
Phone: 404-872-7100 or 800-283-7800 (free of charge)
or call your local chapter (listed in the local telephone directory)
www.arthritis.org
The foundation has several free brochures about
coping with arthritis, taking nonsteroid and steroid medicines,
and exercise. A free brochure on protecting your joints is titled
"Using Your Joints Wisely." The foundation also can
provide addresses and phone numbers for local chapters and physician
and clinic referrals.
Acknowledgments
The NIAMS gratefully acknowledges the assistance
of Barbara Mittleman, M.D., and James Panagis, M.D., M.P.H., NIAMS,
NIH; John H. Klippel, M.D., Arthritis Foundation, Atlanta, Georgia;
Frank A. Pettrone, M.D., Arlington/Vienna, Virginia; and W. Norman
Scott, M.D., Beth Israel Medical Center, New York, New York, in
the preparation and review of this booklet.
The mission of the National Institute of Arthritis
and Musculoskeletal and Skin Diseases (NIAMS) is to support research
into the causes, treatment, and prevention of arthritis and musculoskeletal
and skin diseases; the training of basic and clinical scientists
to carry out this research; and the dissemination of information
on research progress in these diseases. The NIAMS Information
Clearinghouse is a public service sponsored by the NIAMS that
provides health information and information sources. Additional
information and research updates can be found on the NIAMS Web
site at http://www.niams.nih.gov/.
This booklet is not copyrighted. Readers are encouraged
to duplicate and distribute as many copies as needed.
Additional copies of this booklet are available
from
National Institute of Arthritis and Musculoskeletal
and Skin Diseases (NIAMS) Information Clearinghouse
National Institutes of Health (NIH)
1 AMS Circle
Bethesda, MD 20892-3675
